1. Technical Field
Embodiments of the invention relate generally to power converters. Other embodiments relate to braking power converters for use with electric wheel brakes usable in off-highway vehicles (“OHVs”), such as mining trucks, locomotives, and the like, and other vehicles.
2. Discussion of Art
Power supplies are electronic/electrical circuits that supply electric power to one or more electric loads. The term “power supply” is most commonly applied to collections or an assembly of electrical devices that convert one form of electrical energy to another, which are commonly referred to as “power converters.” Many power supplies include two or more power converters connected together. Typically, power converters are “switching” power converters, in which multiple solid state devices are to used to intermittently interrupt an input current so as to effectuate conversion of the input current to an output current having different amplitude, voltage, and/or frequency. For example, a “DC power converter” produces output power at a substantially constant output voltage and/or current.
Conventional power converters, generally, are groupings of plural solid state switches that are connected to output terminals from a first DC input terminal or from a second DC input terminal. The two DC terminals typically are known jointly as a “DC link,” while the term “DC link voltage” often is used to refer to a potential difference across this DC link.
Typically, power converters are designed to drive specific loads (e.g., motors or actuators). However, power converters also can be designed to be driven by specific sources. For example, a braking power converter can be driven by voltage generated at an electric wheel during braking. The generated voltage and/or frequency will vary depending on the rotational speed of the wheel being braked. A braking power converter can be modulated to permit or prevent current from the electric wheel brake to a resistive load, thereby modulating the braking power of the electric wheel brake. However, each of the power converter switch modules has a maximum current that limits the achievable braking power. The maximum current limit is determined, in part, by the available forward conducting area within the switch module.